Reduction of organic carbonyl compounds



7 Patented a. 1a, 1931 l EDUAR-D Iauinwcir, eaLunwiersrraruinouamen-Brunei,f GERMANY; Ann atron VOLTZ, on BASLE,SWITZERLAND, ass euons 52130 GENERAL ANILIIN'E wonxs, 1am,

. or NEW YORILYN.Y.,A'G'OB-BOBATIO1\T or D LAWARE .j"

nnnuc'rion or oneAi ic oi 'aBoNYn oomrounns No Drawing. Applicationfiled August 1928 SerialINb. 29 G,8 62, a1 1 d. in" .Geirmany. Aug11513212, i927;

lVe have found that vat dyestuffspor other organic substances which likethe vat dyestuffs, contain reducible carbonyl or quinone groups, areVery easily and smoothly reduced if treated, in the presence of-organicbases, with metals and sulfurous acid wh ch expression also includesacidsaltsof sulfurousacid with or without the use of diluents.

. products as they The easy and quantitative reduction by means ofmetals andsulfurousacid which takes place almost instantaneously evenwhen anhydrous bases areemployed, has the advantage that the resultingleuco compounds can be at once transformed in the reaction mixture, intoesters by treatment acid or esters of V chlorid, acetic anhydridand thelike. In this way not'only is the work simplified, but the products arealso often obtained in a purer state and in a higher yield than by othermethods. In some cases the acylating agent may be added alreadyin thecourse of the reduction or imined'ately thereafter directly to thereaction mixture. The reduc q tionproducts may also be first isolated byfiltra ion or other separate out from the reaction mixture incrystalline form during the reaction or on cooling or diluting thereaction mixture or distilling off the bases and -"f d *frbl.r thedlluents 1 such be a p16 em at once. The m xture-1s stirredatfrom25 to30 QC NWhil'e preventing contact with air,

under diminished pressure. I p

The metals preferably to be' employed according to the present inventioncomprise copper, zinc, iron, aluminium,- and the like,

, used either separately or in mixtures, or also .with-the additlon ofother metals such as 7' magnesium or calcium; they are preferably emloyed in a finely divided state such as metallic powder. Theorganicbasesmay be for example, pyridine, aniline, dimethylaniline,triethanolamine and the like. 1 The following examples will furtherillustrate the nature of the lsaid invention.

The

which however is not limited thereto] parts are by weight.

Example 1; V

wlth acylating agentsfsuch as chlorsulfonic.

same, phosphorus oXymanner or removing the i PY ine of into 5Q parts ofanhydrous pyridine; "where- I 11 5 11 10 parts: of 5.5, 7 .Tte'trabromindigjo aud o parts of copper powder are added at about 159,10. The mixture is stirred while.

On dilution with waterpthe leuco compoundseparates-out as'a lemon yellowsubstance, WhlCll,' 1f -requ1re'd,11s s'ub1ected to further treatmentfor J example to acetyla tion; The resulting solutionof the leucocompound may also directlybe treated with the suitable amount of aceticanhydrid,

whereupon the quantitative .acetylation of theleuco compound;accompanied by a spontaneous risein temperature, occurs in a fewminutes. If the acetic anhydrid be replaced by chlorsulfonic acid, agood-yield of the digo is obtained. ..xv

' Hamper sulfuric ester Gimme-a5, 7-.7-"'-tetralorominf ffi partsbyweight "or di methoaydibeiizaiir throne are suspended in a solution of5.0 parts of pyridine, and '10 parts of sulfurous" acid,

and 4 parts of copper-powder are added to the gmixture at 1 5.? C.-The-reduction begins whereupon the dark red solution of the leucocompound :is formed. Increasing the tem perz'iturefor example; to; ;C'.,accelerates" the reduction. If 10 parts of acetic anhy-,

compound takes place'in: a few minutes, and onthe'. resultmgorangefi'red solution being fate. I V

Eacample" I Ami-xture of 25'parts'by weight ofpure sulfurous acid and 5parts of 5.5, 7.7-tetra- 10 parts of sulfurous acid are introduceb'r'omindigo is treated withafgradualaddi- "dI'ld'QbB. added to theresulting solution at about 30 G., the acetylationof the leucodiluted-withwater, the acetyl compound is I thrown down as ared,inoxidisable precipithe firm of (Merck), 5 parts of Y V tion of 2 partsof zinc dust, at low temperatures, down to C. and While preventingcontact with air. The mixture soon acquires a greenish color, and onremoval from cooling liquid, the dyestutf is rapidly reduced, the

temperature rising spontaneously to from to 0., a yellow suspensionbeing obtained. The lemon yellow leuco compound,

Which-separates out almost completely on dilution With Water, can easilybe subjected to further treatment, being comparatively stable in air.

If the pyridine be replaced by other bases,

as for example a commercial mixture of 15 pyridine bases, ordimethyl-aniline or aniline or if the Zinc be replaced by other metalssuch as iron, aluminium, or metallic mixtures lilre'Devardas alloyconsisting of parts of aluminium, parts of copper and 5 parts of zinc(see, for example, .Chemiker Zeitung (1892) Vol. 16, p. 1952), reductionalso takes place. In such cases the presence of small amounts of Waterand increased temperatures often has a favourable influence on thevelocity of the reduction.

' Other Vat dyestuffs, such as indigo, thioindigo, and the like, orother reducible substances, such as arylidoquinones,phenanthrenequinone, and many others, can also be reduced in a similarmanner.

W hat We claim is:

1. The process of manufacturing reduction products Which comprisessubjecting an or anic compound containing a reducible carbonyl group ,tothe action of sulfurous acid and a metal in the presence of an organicbase.

2. The process of manufacturing reduction products which comprises Subecting an organic compound containing. a reducible carbonyl group to theaction of sulfurous acid and a metal in the presence of an organic baseand treating the reaction mass With an acylating agent i '3 3. Theprocess which comprises subjecting vat dyestuffs to the action ofsulfurous acid and a metal in the presence of an organic base. v

4. The process whichcomprises'subjecting 5 vat dyestuffs to the actionof sulfurous acid and a metal selected from the group consisting ofcopper and zinc, in the presence of an organic base.

In testimony whereof We have hereunto our hands. 1 EDUARD MUENCH.

THEODOR VOLTZ.

